Three-dimensional simulation technology is widely employed in the development of high-power density diesel engines due to its efficiency and cost-effectiveness. However, its application is often constrained by the lack of effective methods for evaluating the accuracy of simulation models. Taking a constant-volume diesel spray simulation model as the subject, the sensitivity coefficient method was used to determine the influence trend and degree of 13 key parameters such as initial spray conditions, breakup models and turbulence models on both liquid and vapor phase spray penetration distances. Based on the analysis, the simulation model was calibrated through optimal parameter configuration, and its accuracy was evaluated using statistical methods. The results indicate that the simulation accuracy for liquid phase penetration reaches 93.11%, while that for vapor phase penetration reaches 95.95%. The proposed model calibration and accuracy evaluation methodology can be extended to the simulation of diesel engine working processes, providing theoretical support and technical reference for the practical application of three-dimensional simulation technology in the development of high-power density diesel engines.